1150 Macromolecules, Vol. 43, No. 2, 2010
Miyake and Chujo
purification. Tributylphosphine (P(Bun)3) and triphenylphos-
phine (PPh3) were purchased from Wako Chemical, Co. Ltd.
Measurements. 1H (400 MHz) and 13C (100 MHz) NMR
spectra were recorded on a JEOL JNM-EX400 spectrometer
utilizing 0.05% tetramethylsilane (TMS) as an internal standard
in CDCl3 at room temperature. Number-average molecular
weight (Mn) and molecular weight distribution value (Mw/Mn)
of all polymers were estimated on a TOSOH size exclusion
chromatography (SEC) system equipped with a polystyrene gel
column (TOSOH gel: G3000HXL) using refractive-index (RI-
8020) and ultraviolet (UV-8020) detectors at 40 °C. The system
was operated at a flow rate of 1.0 mL/min with CHCl3 as an
eluent after calibration with the standard polystyrene samples.
FT-IR spectra were obtained on a Perkin-Elmer 1600 infrared
spectrometer. UV-vis spectra were recorded on a Shimadzu
UV-3600 spectrophotometer at room temperature. Elemental
analysis was performed at the Microanalytical Center of Kyoto
University.
Methyl 4-Azido-3-hydroxybenzoate (2). A round-bottomed
flask was charged with 5.00 g (30.0 mmol) of methyl 4-amino-
3-hydroxybenzoate (1) dissolving 100 mL of aqueous solution.
After cooling down to 0 °C, 25 mL of conc. H2SO4, 2.76 g
(40.0 mmol) of NaNO2, and 3.25 g (50.0 mmol) of NaN3 were
then added dropwise. The reaction mixture was left to stir for
12 h at room temperature. The mixture was extracted with
EtOAc, washed with H2O, and the organic layer was dried over
MgSO4. Afterward, the solvent was removed with a rotary
evaporator, and the crude product was purified by flash chro-
matography on silica with an eluent of hexane/EtOAc adjusted
to give an Rf for the product of 0.2-0.3. Yield: 87%. 1H NMR
(400 MHz, CDCl3): δ (ppm) 7.56 (d, 1 H), 7.54 (s, 1 H), 6.99 (d, 1
H), 6.60-5.75 (br, 1 H), 3.83 (s, 3 H). 13C NMR (100 MHz,
CDCl3): δ (ppm) 166.6 (CH3OOC), 147.4 (CAr-N), 131.1
(CAr-C), 127.4 (CAr-O), 122.6 (CAr-H), 118.4 (CAr-H),
117.2 (CAr-H), 52.3 (CH3OOC). MS (EI) m/z: 193.0488
(C8H7N3O3 requires 193.0487).
(CAr-O), 133.0 (CAr-C), 127.1 (CAr-N), 122.7 (CAr-H), 120.2
(CAr-H), 113.3 (CAr-H), 67.6 (CH2O), 52.1 (CH3OOC), 40-19
(aliphatic carbons). MS (EI) m/z: 333.2049 (C18H27O3N3 re-
quires 333.2052). Anal. Calcd: C 64.84, H 8.16, N 12.60, O 14.40.
Found: C 64.69, H 8.05, N 12.50, O 14.61.
General Procedure for 4-Azido-3-alkoxybenzaldehydes (M1a,
b). A round-bottomed flask was charged with methyl 4-azido-3-
alkoxybenzoates dissolving CH2Cl2 solution. After the reaction
was allowed to cool down to -78 °C, a large excess of DIBAL-H
(1.0 M hexane solution) was added dropwise. The reaction
mixture was then left to stir for 1 h at -78 °C, after which the
reaction was quenched by adding a large excess of MeOH. After
warming up to room temperature, the solution was poured into
aqueous potassium sodium tartrate, and the resulting mixture
was stirred for 1 h. The mixture was diluted with CH2Cl2 and
washed with H2O, and the organic layer was dried over MgSO4.
Afterward, the solvent was removed with a rotary evaporator,
and the crude product was purified by flash chromatography on
silica with an eluent of hexane/EtOAc adjusted to give an Rf for
the product of 0.2-0.3. Then, a solution of 4-azido-3-alkoxy-
benzyl alcohols in CH2Cl2 was added to a stirred solution of
Dess-Martin periodinane (DMP) in CH2Cl2 over 5 min. The
solution came to a spontaneous boil for about 5 min. After 1 h,
the solution was poured into saturated aqueous NaHCO3
containing Na2S2O3, and the resulting mixture was stirred for
1 h. The mixture was diluted with CH2Cl2 and washed with H2O,
and the organic layer was dried over MgSO4. Afterward, the
solvent was removed, and the crude product was chromato-
graphed on silica with an eluent of hexane/EtOAc adjusted to
give an Rf for the product of 0.2-0.3.
4-Azido-3-methoxybenzaldehyde (M1a). The reaction was
carried out by following the procedure described above. Yield:
60%. 1H NMR (400 MHz, CDCl3): δ (ppm) 9.90 (s, 1 H), 7.44
(d, 1 H), 7.41 (s, 1 H), 7.12 (d, 1 H), 3.96 (s, 3 H). 13C NMR (100
MHz, CDCl3): δ (ppm) 190.6 (CHO), 152.5 (CAr-O), 135.0
(CAr-C), 133.9 (CAr-N), 125.3 (CAr-H), 120.3 (CAr-H), 110.1
(CAr-H), 56.1 (CH3O). MS (EI) m/z: 177.0536 (C8H7O2N3
requires 177.0538). Anal. Calcd: C 54.24, H 3.98, N 23.72, O
18.06. Found: C 54.27, H 3.91, N 23.58, O 18.30.
General Procedure for Methyl 4-Azido-3-alkoxybenzoates (3a,
b). A round-bottomed flask was charged with methyl 4-azido-
3-hydroxybenzoate (2) and a large excess of the corresponding
alkyl halides. To this were added a large excess of anhydrous
K2CO3, anhydrous acetone, and a stir bar. The reaction mixture
was then left to stir for 12 h at 80 °C, after which the solvent was
removed via vacuum distillation. CH2Cl2 was then added to the
residue, and the resulting suspension was filtered to remove
excess K2CO3 and insoluble byproducts. Afterward, the solvent
was removed with a rotary evaporator, and the crude product
was purified by flash chromatography on silica with an eluent of
hexane/EtOAc adjusted to give an Rf for the product of 0.2-0.3.
Methyl 4-Azido-3-methoxybenzoate (3a). The above general
procedure was performed with 1.93 g (10.0 mmol) of methyl 4-
azido-3-hydroxybenzoate (2), 25.0 g (176.0 mmol) of methyl
iodide, 8.30 g (60.0 mmol) of K2CO3, and 50 mL of acetone. The
crude product was purified by column chromatography to give
4-Azido-3-(30,70-dimethyloctyloxy)benzaldehyde (M1b). The
reaction was carried out by following the procedure described
above. Yield: 65%. 1H NMR (400 MHz, CDCl3): δ (ppm) 9.88
(s, 1 H), 7.42 (d, 1 H), 7.40 (s, 1 H), 7.06 (d, 1 H), 4.13 (t, 2 H),
1.90 (m, 1 H), 1.80-0.80 (br, 18 H). 13C NMR (100 MHz,
CDCl3): δ (ppm) 190.6 (CHO), 152.4 (CAr-O), 134.8 (CAr-C),
133.8 (CAr-N), 125.0 (CAr-H), 120.1 (CAr-H), 110.7 (CAr-H),
67.7 (CH2O), 40-19 (aliphatic carbons). MS (EI) m/z: 303.1945
(C17H25O2N3 requires 303.1947). Anal. Calcd: C 67.30, H 8.31,
N 13.85, O 10.55. Found: C 67.10, H 8.21, N 13.78, O 10.85.
Polymerization Procedure. A general polymerization proce-
dure is as follows. In a round-bottom flask were placed a
monomer, dry toluene (200 mM), and an excess amount of
phosphine at room temperature. The reaction mixture was
thoroughly deoxygenated, filled with high-purity argon, and
placed in a thermostatic oil bath at 80 °C for 72 h. After cooling
down, the reaction mixture was concentrated. Exhaustive ex-
traction of the resulting solid with methanol (Soxhlet extraction)
afforded the target polymer. P1a: IR (ν, cm-1): 1575
(-CHdN-). P1b: 1H NMR (400 MHz, CDCl3): δ (ppm) 8.50
(br, 1 H), 7.65 (br, 1 H), 7.10 (br, 2 H), 4.15 (br, 2 H), 1.95-0.80
(br, 19 H). IR (ν, cm-1): 1575 (-CHdN-).
1
3a (82% yield, 1.70 g). H NMR (400 MHz, CDCl3): δ (ppm)
7.63 (d, 1 H), 7.55 (s, 1 H), 7.00 (d, 1 H), 3.91 (s, 3 H), 3.89 (s, 3
H). 13C NMR (100 MHz, CDCl3): δ (ppm) 166.2 (CH3OOC),
151.6 (CAr-O), 133.1 (CAr-C), 127.2 (CAr-N), 123.0 (CAr-H),
119.8 (CAr-H), 112.7 (CAr-H), 56.0 (CH3O), 52.1 (CH3OOC).
MS (EI) m/z: 207.0642 (C9H9N3O3 requires 207.0644). Anal.
Calcd: C 52.17, H 4.38, N 20.28, O 23.17. Found: C 51.72, H
4.40, N 20.26, O 23.67.
Methyl 4-Azido-3-(30,70-dimethyloctyloxy)benzoate (3b). The
above general procedure was performed with 1.93 g (10.0 mmol)
of methyl 4-azido-3-hydroxybenzoate (2), 6.00 g (27.0 mmol) of
1-bromo-3,7-dimethyloctane, 8.30 g (60.0 mmol) of K2CO3, and
50 mL of acetone. The crude product was purified by column
chromatography to give 3b (72% yield, 2.40 g). 1H NMR (400
MHz, CDCl3): δ (ppm) 7.58 (d, 1 H), 7.55 (s, 1 H), 6.94 (d, 1 H),
4.10 (t, 2 H), 3.90 (s, 3 H), 1.90 (m, 1 H), 1.80-0.80 (br, 18 H).
13C NMR (100 MHz, CDCl3): δ (ppm) 166.3 (CH3OOC), 151.6
References and Notes
(1) (a) Iwan, A.; Sek, D. Prog. Polym. Sci. 2008, 33, 289–345. (b) Pron,
A.; Rannou, P. Prog. Polym. Sci. 2001, 27, 135–190.
(2) (a) Marvel, C. S.; Hill, W. S. J. Am. Chem. Soc. 1950, 72, 4819–
4820. (b) Yang, C. J.; Jenekhe, S. A. Chem. Mater. 1991, 3, 878–
887.
(3) (a) Fischer, W.; Stelzer, F.; Meghdadi, F.; Leising, G. Synth. Met.
1996, 76, 201–204. (b) Weaver, M. S.; Bradley, D. D. C. Synth. Met.